Field of the Invention
The field of the invention is high frequency switching power converters, and, more particularly, resonant switching converters.
It is desirable to increase switching frequencies in DC-DC power switching converters to reduce the size and weight of transformer and filter components in DC-DC power converters. In order to keep the switching power losses low and to reduce the problem of electro-magnetic interference (EMI) resonant concepts have been proposed to allow zero-voltage and/or zero-current switchings so as to minimize switching losses. In such resonant converters, the output voltage is regulated by controlling the switching frequency. This has the drawback of making the control and the EMI filter design more complicated. Recently constant frequency control of resonant converters has been described in F. Tsai, P. Materu, and F. C. Lee, "Constant Frequency, Clamped-Mode Resonant Converters," IEEE PESC Record 1987, pp. 557-566 and I. J. Pital, "Phase-Modulated Resonant Power Conversion Techniques for High Frequency Inverters," IEEE IAS Annual Meeting, Proceedings 1986.